Added E2E tests

[hql287]

Description

Related Issue

Issue #248

Motivation and Context

While unit tests are helpful in testing parts of the application. E2E tests make sure these parts do work together as a whole.

How Has This Been Tested?

Right now, passed tests include:

• [x] App does start up and open 3 windows
• [x] Create the tourWindow with the correct title, size, properties and state.
• [x] Place the tourWindow in the centre of the primary display.
• [x] App creates mainWindow with the correct title, size, properties and states.
• [x] App creates previewWindow with the correct title, size, properties and states.

TODO:

• [ ] Testing Application Menu

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.
• [ ] I have included a migration scheme (If type of change is breaking change)